1. Field of the Invention
The present disclosure relates to a head part of an annular combustion chamber and particularly but not exclusively relates to a head part of an annular combustion chamber for a gas turbine.
The operation of gas turbine engines is relatively well known and, as will be appreciated, requires presentation of fuel for combustion in order to generate thrust. In order to present that fuel, a fuel spray nozzle or burner is required. A plurality of burners may be provided about the annulus of an annular combustion chamber.
2. Description of the Related Art
Referring to FIG. 1, which shows a previously-proposed arrangement, the fuel burner (not shown) is typically located within an end wall or meter panel 10 such that the fuel spray is appropriately presented within the combustor parts of the gas turbine engine. It will be understood that the combustor parts of a gas turbine engine will generate significant heat and therefore thermal stressing as well as vibration and other factors may create significant wear upon the mountings for the spray nozzle. In such circumstances a burner collar 30 is generally provided within the end wall 10 which ensures that the fuel spray nozzle is appropriately presented. A heat shield 20 is also provided to protect the end wall 10 from the hot burner gases and from an unacceptably high radiation effect. Furthermore, upon repair and overhaul it is generally easier to replace the heat shield 20 rather than the end wall 10 within the gas turbine engine.
In the previously-proposed arrangement shown in FIG. 1, the burner collar 30 is held between first and second location rings 34, 36, which are in turn held in place between the heat shield 20 and a protruding portion 12 of the end wall 10. The heat shield 20 is fastened to the end wall 10 to secure the arrangement.
The first location ring 34 is provided between the burner collar 30 and end wall 10. The end wall 10 may be cast and the back side of the end wall (i.e. the side facing the combustion chamber) may not be machined smooth. The first location ring 34 therefore provides a flat surface for the burner collar 30 to rest on. The location rings 34, 36 may be laser cut or machined.
The protruding portion 12 of the end wall 10 first extends away form the combustion chamber side of the end wall 10 and then radially inwardly. Accordingly, the protruding portion 12 of the end wall 10 provides a surface set back from the remainder of the end wall 10 for the first location ring 34 to rest on. The protruding portion 12 of the end wall 10 is cast integral with the remainder of the end wall 10.
Other examples of other previously-proposed arrangements are shown in U.S. Pat. No. 5,996,335, EP1975514, U.S. Pat. No. 5,956,955 and U.S. Pat. No. 5,894,732.
The protruding portion 12 of the end wall 10 adds cost, weight and complexity to the end wall 10 casting. Furthermore, the positional tolerances achievable with a cast surface require that the end wall 10 protruding portion 12 is thicker and heavier than its function requires. This additional weight is disadvantageous particularly in the case of a jet engine gas turbine.
The present disclosure therefore seeks to address these issues.